/Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/Operations/IntrinsicCorrespondenceUtils.h
Update the NormalCoords and RoundaboutOrder after an intrinsic mesh edge flip. TriAEID, and TriBEID are the triangle edges of the two affected triangles prior (!) to flipping the specified edge.
false if something failed
bool OnFlipEdge ( const int32 T0ID, const [FIndex3i](API\Runtime\GeometryCore\FIndex3i) & BeforeT0EIDs, const int32 T0OppVID, const int32 T1ID, const [FIndex3i](API\Runtime\GeometryCore\FIndex3i) & BeforeT1EIDs, const int32 T1OppVID, const int32 FlippedEID )